I'm new to WPF and MVVM. I think this is a simple question. My ViewModel is performing an asynch call to obtain data for a DataGrid which is bound to an ObservableCollection in the ViewModel. When the data is loaded, I set the proper ViewModel property and the DataGrid displays the data with no problem. However, I want to introduce a visual cue for the user that the data is loading. So, using Blend, I added this to my markup:

        <VisualStateManager.VisualStateGroups>
        <VisualStateGroup x:Name="LoadingStateGroup">
            <VisualState x:Name="HistoryLoading">
                <Storyboard>
                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="HistoryGrid">
                        <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/>
                    </ObjectAnimationUsingKeyFrames>
                </Storyboard>
            </VisualState>
            <VisualState x:Name="HistoryLoaded">
                <Storyboard>
                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="WorkingStackPanel">
                        <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/>
                    </ObjectAnimationUsingKeyFrames>
                </Storyboard>
            </VisualState>
        </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>

I think I know how to change the state in my code-behind (something similar to this):

VisualStateManager.GoToElementState(LayoutRoot, "HistoryLoaded", true);

However, the place where I want to do this is in the I/O completion method of my ViewModel which does not have a reference to it's corresponding View. How would I accomplish this using the MVVM pattern?